Phytochemical Analysis and Antimicrobial Evaluation of Essential Oils from Eucalyptus tereticornis Sm.

Abstract: This study investigates the phytochemical composition and antimicrobial properties of essential oils extracted from Eucalyptus tereticornis Sm. Using gas chromatography-mass spectrometry (GC-MS) and in vitro antimicrobial assays. Essential oils were extracted from the leaves of Eucalyptus tereticornis through hydrodistillation, yielding 2.5% (v/w) of oil. GC-MS analysis identified 32 compounds, with 1,8-cineole (45.2%), α-pinene (15.8%), and β-pinene (9.3%) being the predominant constituents. The antimicrobial activity of the essential oils was tested against a range of pathogenic microorganisms, including Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa), and fungi (Candida albicans and Aspergillus niger), using the broth microdilution method. The essential oils exhibited significant antimicrobial activity, with minimum Inhibitory concentration (MIC) values ranging from 0.25 to 2.0 mg/mL. The lowest MIC value of 0.25 mg/mL was observed against Staphylococcus aureus, while Candida albicans and Escherichia coli showed MIC values of 1.0 mg/mL and 0.5 mg/mL, respectively. Minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) values were generally one dilution higher than the MIC values, confirming the bactericidal and fungicidal properties of the oils.